Before there was CGI, there were mechanical monsters powered by electric motors. This dinosaur might not have been real, but grabbing an actress and lifting her several feet in the air is no easy feat. While standing on the operating platform within the dinosaur's belly, two men would shift counterweights to balance the weight of the dinosaur's head after it seized the actress. Motors and gears below the counterweights would lift the legs to make it appear as if the dinosaur were walking. Another set of gears attached to a crane would rotate the tail. Even smaller motors allowed the dinosaur to blink and roll its eyes to appear more lifelike.
Read the full story in "Mechanical Monster 'Eats' Girl on Movie Stage"